The present invention relates to a diamond tool suitable for mirror-finish cutting of workpieces of non-ferrous metallic materials such as aluminum and copper and a method of manufacturing the same.
As is described in Jap. Pat. Pub. Nos. 58-10164 and 58-58162, a conventional tool is formed in a tool profile capable of cutting a workpiece in a satisfactory surface roughness and reducing scratches, on an assumption that the tool profile of the tool is transferred perfectly to the workpiece. However, in designing such a tool, no consideration is given with respect to tears in cutting a workpiece formed of a material of a cellular texture such as, for example, an aluminum alloy, and the reduction of residual stress in the workpiece through the reduction of cutting force.
In practical mirror-finish machining operation, the angle of the end cutting edge of a cutting tool to the direction of feed, namely, the entering angle, needs to be determined properly to prevent tears in the machined surface. However, no consideration has been given with respect to geometric surface roughness in designing the conventional tool.
Furthermore, no consideration is given to most single crystal diamond tools with respect to wear. Jap. Pat. Pub. No. 58-37082 refers to the wear of a diamond tool and infers that the burnishing effect of the back clearance face thereof exerted on a surface cut by the side clearance face thereof enables the mirror-finish cutting of the diamond tool. Therefore, Jap. Pat. Pub. No. 58-37082 provides a diamond tool having a back clearance face aligned with a crystal orientation appropriate for the moderate abrasion of the back clearance face, namely, a crystal orientation intermediate the orientations (110) and (010). Accordingly, the moderate abrasion of the diamond tool is necessary for mirror-finish cutting. Therefore, such a diamond tool is unsatisfactory in respect of abrasion resistance, and the possible cutting distance of the diamond tool in cutting an aluminum-magnesium alloy is 200 km or less.